Fix error when adding a scheduled transaction
Set the account reference when creating the transaction to prevent MyMoneyTransaction::addSplit from erroring because its accountId wasn't set with this message:
Unable to add scheduled transaction: Cannot add split that does not contain an account reference .../kmymoney/mymoney/mymoneytransaction.cpp:210
This issue was introduced in c0ab1dc1.
Not sure if this is the correct way to fix this -- it seems to work, at least.